Anatomy is the study of the biological structure of living things. The term comes from the Greek words meaning to cut up, because knowledge of anatomy was first obtained through dissection. The bodies of human beings and animals are so complex that scientists divide anatomy into many branches. Gross anatomy is the study of structures that can be seen with the unaided eye. Microscopic anatomy, or histology, is the study of tissues under a microscope. Comparative anatomy compares the structure of different animals. Embryology is the study of the development of plants and animals in their earliest stages.